import java.util.Scanner;

public class shijianlvxing {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            String a = in.next();
            String b = in.next();
            int len = a.length();
            int len1 = b.length();
            char[] c = a.toCharArray();
            char[] d = b.toCharArray();
            int[] e = new int[len];
            int[] f = new int[len1];
            int aa = 0, bb = 0;
            for (int i = 0; i < len; i++) {
                if (c[i] >= '0' && c[i] <= '9') {
                    e[aa] = c[i] - 48;
                    aa++;
                }
            }
            for (int i = 0; i < len1; i++) {
                if (d[i] >= '0' && d[i] <= '9') {
                    f[bb] = d[i] - 48;
                    bb++;
                }
            }
            int[] q = new int[len];
            int[] n = new int[len];
            for (int i = 0; i < aa; i++) {
                q[i] = e[i] * 10 + e[i + 1];
            }
            for (int i = 0; i < bb; i++) {
                n[i] = f[i] * 10 + f[i + 1];
            }

                int m = 0, w = 0;
                for (int i = 0; ; i++) {
                    q[2]++;
                    m++;
                    if (m == 60) {
                        m = 0;
                        w++;
                    }
                    if (q[2] == 60) {
                        q[2] = 0;
                        q[0]++;
                        if (q[0] == 24) {
                            q[0] = 0;
                        }
                    }
                    if (q[0] == n[0] & q[2] == n[2]) break;
                }
                if (w < 10|m < 10) {
                    if (w<10&m ==0)
                        System.out.println("0" + w + ":" + "0" + "0");
                    if(w<10&m<10&m!=0)
                        System.out.println("0" + w + ":" +"0"+ m);
                    if(w<10&m>10)
                        System.out.println("0" + w + ":" + m);
                    if(w>10&m<10)
                        System.out.println(w + ":" +"0"+ m);
                }
                else
                    System.out.println(w + ":" + m);
            }
        }
    }
